What determines echogenicity in a general population? The Tromsø Study

Noninvasive localization of cardiac arrhythmias using electromechanical wave imaging

Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. The 12-lead electrocardiogram (ECG) is the current noninvasive clinical tool used to diagnose and localize cardiac arrhythmias. However, it has limited accuracy and is subject to operator bias. Here, we present electromechanical wave imaging (EWI), a high-frame rate ultrasound technique that can noninvasively map with high accuracy the electromechanical activation of atrial and ventricular arrhythmias in adult patients. This study evaluates the accuracy of EWI for localization of various arrhythmias in all four chambers of the heart before catheter ablation. Fifty-five patients with an accessory pathway (AP) with Wolff-Parkinson-White (WPW) syndrome, premature ventricular complexes (PVCs), atrial tachycardia (AT), or atrial flutter (AFL) underwent transthoracic EWI and 12-lead ECG. Three-dimensional (3D) rendered EWI isochrones and 12-lead ECG predictions by six electrophysiologists were applied to a standardized segmented cardiac model and subsequently compared to the region of successful ablation on 3D electroanatomical maps generated by invasive catheter mapping. There was significant interobserver variability among 12-lead ECG reads by expert electrophysiologists. EWI correctly predicted 96% of arrhythmia locations as compared with 71% for 12-lead ECG analyses [unadjusted for arrhythmia type: odds ratio (OR), 11.8; 95% confidence interval (CI), 2.2 to 63.2; P = 0.004; adjusted for arrhythmia type: OR, 12.1; 95% CI, 2.3 to 63.2; P = 0.003]. This double-blinded clinical study demonstrates that EWI can localize atrial and ventricular arrhythmias including WPW, PVC, AT, and AFL. EWI when used with ECG may allow for improved treatment for patients with arrhythmias.

Subclinical and clinical correlates of left ventricular wall motion abnormalities in the community

The prevalence and clinical correlates of left ventricular (LV) wall motion abnormalities (WMAs), associated with morbidity and mortality, have not been well-characterized in the population. Framingham Heart Study Offspring Cohort participants (n = 1,794, 844 men, age 65 ± 9 years) underwent cine cardiovascular magnetic resonance for evaluation of LV function. A subset (n = 1,009, 460 men) underwent cardiac multidetector computed tomography for analysis of coronary artery calcium. The presence of coronary heart disease and heart failure (CHD-HF) were assessed in relation to the presence of WMAs. WMAs were present in 117 participants (6.5%) and were associated with male gender, elevated hemoglobin A1c, LV mass, LV end-diastolic volume, and lower LV ejection fraction. Of the 1,637 participants without CHD-HF, 68 (4.2%) had WMAs. In this group, WMAs were associated with obesity, hypertension, and Framingham coronary heart disease risk score in the age- and gender-adjusted analyses and were associated with male gender and hypertension on multivariate analysis. Most subjects with WMAs were in the greatest coronary artery calcium groups. The presence of coronary artery calcium greater than the seventy-fifth percentile and Agatston score >100 were associated with a greater than twofold risk of WMAs in the age- and gender-adjusted analysis but were no longer significant when additionally adjusted for CHD-HF. Previous Q-wave myocardial infarction was present in 29% of the 117 participants with WMAs. In conclusion, in the present longitudinally followed free-living population, 4.2% of the participants without CHD-HF had WMAs. WMAs were associated with the clinical parameters associated with cardiovascular disease risk. Aggressive risk factor modification may be prudent for subjects with WMAs, particularly those free of clinical CHD-HF.

Anatomic m-mode, a pertinent tool for the daily practice of transthoracic echocardiography

OBJECTIVES

We sought to compare anatomic M-mode (AMM), a new echocardiographic postprocessing option, and conventional M-mode (CMM) using fundamental imaging and tissue harmonic imaging.

METHODS

Transthoracic echocardiography was performed in 15 selected patients to analyze the reproducibility of AMM and in 47 patients to assess its clinical value versus CMM. Acquisitions were performed successively: CMM fundamental imaging; CMM tissue harmonic imaging; tissue harmonic imaging cineloops for AMM; and fundamental imaging cineloops for AMM. Quantitative analysis was performed offline. The angle alpha between the CMM line and the septal endocardial interface was calculated and the expected percentage of error in measuring left ventricular diameter was derived.

RESULTS

AMM analysis was reproducible. Optimal AMM full echocardiographic definition was obtainable in 77% of the population, whereas CMM was optimal for 49% because of scan line misalignment, causing a measurement overestimation exceeding 5%.

CONCLUSION

The ability with AMM to reduce the alpha angle to 0 degrees and, thus, avoid overestimation of left ventricular dimensions might improve follow-up in several pathologic conditions.

Association between ghrelin and cardiovascular indexes in healthy obese and lean men

OBJECTIVE

Obesity is an increasingly common condition and is associated with excess morbidity and mortality, including clinical and subclinical cardiac dysfunction. The role of hormones involved in energy homeostasis, including ghrelin and leptin, in cardiovascular function remains incompletely understood. Therefore, we sought to evaluate the association between systemic ghrelin and leptin levels with indexes of cardiovascular structure and function.

DESIGN AND MEASUREMENTS

We measured serum ghrelin and leptin levels in 25 clinically healthy obese men and 25 lean controls, using commercially available immunoassays. We also assessed right and left ventricular structure and function using cardiac magnetic resonance imaging. We then investigated the association between serum ghrelin and leptin levels with cardiac indexes, using univariate and multivariate analysis.

RESULTS

There was an independent association between serum ghrelin levels and height-adjusted right ventricular mass (r = -0.324, P = 0.026), right ventricular end-diastolic volume (r = -0.363, P = 0.017) and right ventricular end-systolic volume (r = -0.398, P = 0.009) as well as right ventricular ejection fraction (r = 0.317, P = 0.050). There was no significant association between serum ghrelin and indexes of left ventricular structure or function. We also identified an association between serum leptin levels and resting heart rate (r = 0.391, P = 0.002). There was an association between serum leptin and height-adjusted left ventricular mass on univariate, but not on multivariate, analysis.

CONCLUSIONS

Serum ghrelin is associated with right ventricular cardiovascular indexes and serum leptin is associated with resting heart rate. These associations indicate a close interaction between the endocrine and cardiovascular systems in obesity.

Imagent improves endocardial border delineation, inter-reader agreement, and the accuracy of segmental wall motion assessment

BACKGROUND

This study was conducted to assess the ability of a new echocardiographic contrast agent, Imagent (perflexane lipid microspheres; Alliance Pharmaceutical Corp., San Diego, CA), to improve endocardial border delineation (EBD) and assessment of segmental wall motion (SWM). This was achieved by analysis of inter-reader agreement by echocardiography and comparison with an independent imaging technique, magnetic resonance imaging (MRI).

METHODS

Two separate, independent, prospective, randomized, controlled, multicenter trials were conducted at 26 centers and included a total of 409 efficacy-evaluable patients. In Study A 206 patients were randomized to receive either Imagent or saline and in Study B, 203 patients received Imagent with a subset imaged by both echocardiography and MRI. All patients were required to have suboptimal baseline images using fundamental imaging. Images were optimized at baseline prior to contrast and the settings maintained post-contrast. Imagent, a suspension of perfluorohexane-filled spheres with flexible lipid shells, was administered as an IV bolus at 0.125 mg/kg body weight. Gated MRI studies were performed within 48 hours of dosing in a subset of 26 subjects. Six expert independent blinded readers reviewed unpaired noncontrast and contrast exams and scored EBD and SWM. Analysis of inter-reader agreement was performed by comparing the SWM score (1 to 5) recorded by each reader pair. In addition, unanimity between readers for SWM was evaluated. For comparison to MRI, the results from echo readers 4, 5, and 6 were each compared with a single independent MRI reader.

RESULTS

The patients enrolled in these clinical trials displayed markedly suboptimal images with 49% and 71% (Study A and Study B) of the segments determined by the readers to be suboptimal prior to contrast administration. All readers recorded statistically significant (P < 0.0001) improvement in total EBD scores following the administration of Imagent. Comparison of noncontrast SWM scores for each pair of echo readers resulted in agreement in an average of 39%, of segments in Study A, and 31% of the segments in Study B. Use of Imagent improved agreement in SWM scores to 65% in Study A, and 48% of segments in Study B (P < 0.0001) for all reader pairs in both studies. Reader unanimity in SWM scores increased from 13% to 41% of the segments with the administration of Imagent. Blinded review of the noncontrast echo examinations resulted in agreement with MRI derived SWM scores in 15% of the segments. The administration of Imagent improved this agreement to 47%, of the segments (P < pr = 0.0005 for each blinded reader).

CONCLUSIONS

Use of Imagent during echocardiographic imaging improves EBD, providing a significant improvement in inter-reader agreement in SWM evaluation with echo and greater than a threefold improvement in SWM scoring accuracy with MRI.

Effect of increased body mass index on accuracy of two-dimensional echocardiography for measurement of left ventricular volume, ejection fraction, and mass

We used 2- and 3-dimensional echocardiography to determine left ventricular volume, mass, and ejection fraction in overweight (body mass index [BMI] > or = 25 kg/m2), obese (BMI > or = 30 kg/m2), and control (BMI < 25 kg/m2) subjects. Compared with corresponding magnetic resonance imaging measurements, 3-dimensional echocardiography is more accurate than 2-dimensional echocardiography in all patients, but particularly in overweight and obese subjects.